Metallurgical process for the production of polyvalent metals and the coating of articles therewith



United States Patent NIETALLURGICAL PROCESS FOR THE PRODUC- TION 0FPOLYVALENT NETALS AND THE COATING 0F ARTICLES THEREWITH Wilbur W.Castor, Mount Lebanon, Pa.

No Drawing. ApplicatiouDecember 7, 1953, Serial No. 396,764

14 Claims. (Cl. 117-130) This invention is for a metallurgical processfor the production of titanium, zirconium and other di, tri andquadravalent metals, and especially those which, like titanium andzirconium, are not economically reducible from their natural oxide stateby usual smelting or reducing furnace procedures.

Titanium, for example, is abundant in various compounds over the earthssurface, and is in wide demand. It is, however, expensive to producebecause of the difiiculty in reducing it from the compounds in which itoccurs. temperature it reacts with oxygen, nitrogen, hydrogen and carbondioxide, so that normal metallurgical reducing operations are entirelyunsuitable and inoperative, on a practical scale at least, for itsproduction.

Zirconium is likewise diflicult to produce, as are many of thepolyvalent metals, other than the more familiar commercial ones.

An object of the present invention is to provide a new and moreeconomical process for the production of these metals, and a furtherobject is to provide a method for the coating of articles with a surfacefilm or layer of these metals.

It is well known that organic compounds of titanium, zirconium and otherpolyvalent metals may be prepared, including esters. Referring forexample to titanium, esters have been prepared from both the lower andhigher alcohols. Important among these, for my purpose, is butyltitanate, which has more stability than ethyl and propyl esters,although these may also be used. Likewise, esters of alcohols higherthan butanol could be used.

These esters are relatively inexpensive to produce, and have heretoforefound use in varnishes and coatings. TiOz, for example, may be reactedwith hydrochloric acid to produce titanium tetrachloride, from whichorthotitanic acid is secured by hydrolysis, this acid then being reactedwith the alcohol, all of which procedures are well known and form nopart of my invention.

If butyl titanate is heated, it decomposes, leaving TiOz as a residue. Ihave discovered, however, that if a relatively small amount of metalliciodine be mixed with the butyl titanate it may then be heated in aninert atmosphere, first to release the butanol and subsequently tosublimate the iodine, leaving the titanium sponge as a residue. It wouldbe expected that iodine would be required in an equivalent mol ratio toform TiI4 as an intermediate compound, but this is not the case and theratio does not appear to be critical. I have discovered that as littleas of the mol equivalent is satisfactory. The iodine apparentlyfunctions as a catalyst or stabilizer rather than as a reagent.

As indicated above, butyl titanate is a desirable ester, rather than theesters of either the higher or lower alcohols, because of the stabilityof this compound, and the fact that butanol is commercially availableand less expensive than the esters of the higher alcohols.

In the practice of my invention, the mixture of butyl Its oxides arehighly refractory, and at elevated Patented June 14, 1955 titanate andiodine is heated in an atmosphere of water vapor. At a temperature of300 to 350 F., the alcohol or other organic components of the compoundare removed, along with some of the iodine. Heating is thereaftercontinued in an inert atmosphere to -a temperature above 711 F., thisbeing the boiling point of titanium tetra iodide, and in the region of800 to 850 F., all of the iodine will be removed by sublimation. Thealcohol and iodine removed in this manner may be condensed and recoveredfor reuse, so that the reagents, except for small amounts, are not lost.The cost of their recovery is, of course, low, and the requiredequipment is known. Helium or argon may be used to provide an inertatmosphere above 350 F. or the operation may be carried out in a vacuum.

As an alternative procedure, some water, as for example about 2% byweight, may be added to the btuyliodine mix, which, upon agitation,causes a polymerization and thickening of the mass. This is notnecessary, but such polymerized material may be thickly spread over anobject, such for example as a ferrous body or sheet. The coated objectis then heated as above to remove butanol and iodine, after which thetemperature is raised to 2000 to 2200 F. or more to fuse the resultingmetal residue to the surface of the object, this all being done in aninert atmosphere or environment. The polymer, because of its bettercovering properties, will coat the surface more evenly and be lesslikely to run or flow ofi the coated sheet. The polymer also may bereduced to metal sponge the same as the unpolymerized mixture in thesame manner.

The same procedures may be followed using the zirconium ester to producezirconium sponge and zirconium coated objects. Silicon and otherpolyvalent metals may also be produced by this process, especiallymetals of the class which are too reactive for reduction by furnacesmelting processes.

Bromine may be used in place of iodine, but with no apparent advantage,and greater difiiculty is involved both in recovery of the bromine andfrom corrosion of equipment.

My invention, as herein disclosed, is much faster and more economicalthan present methods and lends itself to a continuous process.

While I have disclosed the oxide as the starting material, these beingthe most prevalent natural compounds of titanium and zirconium, othercompounds may be used and converted to a chloride, as is now generallyknown to the art.

I claim:

1. The metallurgical method which comprises mixiodine into the ester ofa polyvalent metal and thereafter heating the mix to break down andremove the organic constituents of the compound and sublimate theiodine, leaving the sponge metal of said polyvalent metal as a residue.

2. The metallurgical method as defined in claim 1 in which theesterified polyvalent metal is one of the group consisting of titaniumand zirconium.

3. The metallurgical method as defined in claim 1 in which theesterified metal is one of the group consisting of titanium, zirconiumand silicon.

4. The metallurgical method as defined in claim 1 in which theesterified metal is titanium.

5. The metallurgical method as defined in claim 1 in which theesterified metal is zirconium.

6. The metallurgical method as defined in claim 1 in which theesterified metal is silicon.

7. The metallurgical method as defined in claim 1 in which the iodine isadded in an amount substantially less than the theoretical mol ratio toconvert the metal of the esterified compound to a tetra iodide of themetal.

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8. The metallurgical method as defined in claim 1 in which the heatingis effected in an environment inert to the metal being reduced. U

I 9. The metallurgical method as defined in claim 1 in which about 2% byweight-of .water is added to the ester-iodine mix to polymerize. thesame.

r 10. The metallurgical:method defined in claim 1 in which the ester isbutyl-titanate. i i I 11. The metallurgical method as defined-sin claim1- in which the esterified metal. is'one of;the group which reacts withoxygen :and hydrogen at elevated temperatures and is not amenable to-reduction from its oxide by reducing gases or. smelting. .7

12. The metallurgical method as defined in claim 1 in which theester-iodine mix is applied to the surface of an object and the heatingis continued after sublimation of the iodine to a temperature Where theresidue metal is fused to the surface of the object.

13. The metallurgical method as defined in claim 3 in which theester-iodine mix is applied to the surface of an object and the heatingis continued after sublimation of the iodine to a temperature where theresidue metal is fused to the surface of the object.

14. The method defined in claim 1 in which the organic constituents andiodine are recovered for reuse.

No references cited.

1. THE METALLURGICAL METHOD WHICH COMPRISES MIXIODINE INTO THE ESTER OFA POLYVALENT MATAL AND THEREAFTER HEATING THE MIX TO BREAK DOWN ANDREMOVE THE ORGANIC CONSTITUENTS OF THE COMPOUND AND SUBLIMATE THEIODINE, LEAVING THE SPONGE METAL OF SAID POLYVALENT METAL AS A RESIDUE.12. THE METALLURGICAL METHOD AS DEFINED IN CLAIM 1 IN WHICH THEESTER-IODINE MIX IS APPLIED TO THE SURFACE OF AN OBJECT AND THE HEATINGIS CONTINUED AFTER SUBLIMATION OF THE IODINE TO A TEMPERATURE WHERE THERESIDUE METAL IS FUSED TO THE SURFACE OF THE OBJECT.